Exfoliated clay/surfactant complex for inhibiting microorganisms, viruses or plant pests

ABSTRACT

The present invention provides an exfoliated clay/surfactant complex for inhibiting microorganisms, viruses or plant pests. The weight ratio of the exfoliated clay to the surfactant can range from 99/1 to 1/99. Preferably, the exfoliated clay is an inorganic layered clay on a nano scale and the surfactant is cationic, nonionic, anionic or amphoteric.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an exfoliated clay/surfactant complex,and particularly to an exfoliated clay/surfactant complex for inhibitingmicroorganisms, viruses or plant pests. Therefore, the present inventionis suitable for fields including agriculture, fisheries and soilremediation.

2. Related Prior Arts

Most of drugs or materials for inhibiting microorganisms or viruses, forexample, pesticides sprayed on growing plants or preservatives appliedto agricultural and livestock products, are not only toxic to humanbodies but also ruinous to the environment.

In order to inhibit growth of microorganisms and viruses, propermaterials having smaller volume than them (for example, on a nano scale)can be used. Nano silicate platelets (NSPs) achieved by exfoliating clayare also considered due to their high aspect ratio (averagely, 100×100×1nm3), high surface areas (700 to 800 m²/g) and strong charges (ca.20,000 ions per platelet). However, because of these specialcharacteristics, nanosilicate platelets have different electricalproperties at different pH values. Below the isoelectric point (IEP=pH6.4), surfaces of the NSPs are electrically positive and aggregationwill occur. That is, the NSPs are not suitable to be used alone aseffects thereof could be influenced by pH values.

Accordingly, the present invention provides a method of applying NSPs toinhibiting microorganisms, viruses or plant pests without aggregation.

SUMMARY OF THE INVENTION

The object of the present invention is to provide an exfoliatedclay/surfactant complex which can effectively inhibit growth ofmicroorganisms, viruses or plant pests without self-aggregation.

For the exfoliated clay/surfactant complex of the present invention, theweight ratio of the exfoliated clay to surfactant ranges from 99/1 to1/99, preferably from 99/1 to 50/50, and more preferably from 99/1 to90/10. The exfoliated clay is preferably inorganic layered clay on thenano scale; and more preferably nanosilicate platelets (NSPs). Thesurfactant can be a cationic surfactant, nonionic surfactant, anionicsurfactant or amphoteric surfactant; preferably the surfactant is acationic, nonionic surfactant or anionic surfactant; and more preferablya cationic surfactant. The cationic surfactant can be a quaternaryammonium salt of a fatty amine having 12 to 32 carbon atoms or aquaternary ammonium chloride of a fatty amine having 12 to 32 carbonatoms. The nonionic surfactant can be octylphenol polyethoxylate orpolyoxyethylene alkyl ether.

Preferably, the cationic surfactant is ammonium chloride of tallowhaving 12 to 18 carbon atoms or ammonium chloride of hydrogenatedtallow, quaternary ammonium salt of octadecyl fatty amine, octadecylammonium chloride or alkyl dimethyl benzyl ammonium chloride; and morepreferably alkyl dimethyl benzyl ammonium chloride.

Preferably, the nonionic surfactant is polyoxyethylene alkyl ether,polyoxyethylene stearylcetyl ether, sorbitan esters of fatty acids (forexample, Span® series of MERCK), Polysorbate (for example, Tween® seriesof MERCK), alkylphenol ethoxylates, nonylphenol ethoxylates (NPEOs), orfatty alcohol ethoxylates.

The surfactant suitable for the present invention is exemplified inATTACHMENT 1, which shows good effects of inhibiting bacteria or plantpests.

The method for producing the exfoliated clay/surfactant complex of thepresent invention is: mix the exfoliated clay and the surfactant in asolvent for complexing.

The exfoliated clay and the surfactant are preferably respectivelydissolved in the solvent and then mixed. The solvent is preferablywater.

The exfoliated clay/surfactant complex of the present invention can bedissolved in a solvent and then mixed with plants, for example, sprayingon plants or soil, or mixing in water. The complex can be in water toform a solution having a concentration of about 0.01 to 1 wt %.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the procedure of Example 1.

FIG. 2 shows the procedure of Example 5.

FIG. 3 shows the effects of the NSPs/surfactant complexes of Examples 2,5 and 8 in inhibiting growth of bacteria.

FIG. 4 shows the effects of the NSPs/surfactant complexes with differentweight ratios in inhibiting growth of bacteria.

ATTACHMENTS

ATTACHMENT 1 exemplifies the surfactant suitable for the presentinvention.

ATTACHMENT 2 shows the surfactants and NSPs/surfactant weight ratios ofthe Examples.

ATTACHMENT 3 shows the results of the NSPs/surfactant complexes ininhibiting plant pests.

ATTACHMENT 4 compares the results of banana shoots applied with andwithout the NSPs/surfactant complex of Example 5.

ATTACHMENT 5 compares the results of guava applied with and without theNSPs/surfactant complex of Example 5.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The materials used in the present invention include:

1. Ablumine 1214: Alkyl dimethyl benzyl ammonium chloride, a kind ofammonium chloride of tallow having 12 to 18 carbon atoms or ammoniumchloride of hydrogenated tallow, a cationic surfactant, purchased fromTaiwan Surfactant Co.

2. SINOPOL 1830: Polyoxyethylene stearylcetyl ether, a kind ofpolyoxyethylene alkyl ether, a nonionic surfactant, purchased fromSINO-JAPAN CHEMICAL.

3. SDS: Sodium dodecyl sulfate, an anionic surfactant.

4. Nanosilicate platelets (NSPs): Referring to the following descriptionor U.S. Pat. No. 7,022,299 B2, No. 7,094,815 B2, or No. 7,125,916 B2,Pub. No. 2005-0239943-A1, or Ser. No. 11/464,495.

[Preparing Nanosilicate Platelets (NSPs)]

Step (a): Sodium montmorillonite (Na⁺-MMT) (10 g, 11.5meq, purchasedfrom Nanocor Ind. Co.) is previously dispersed in water (1 L, 80° C.) ina beaker and swelled by vigorously stirring for 4 hours to form anearth-colored uniform dispersion.

Step (b): In a reactor, p-cresol (27.2 g) and poly(propyleneglycol)-diamine (Jeffamine D-2000, 757.6 g) are dissolved in toluene(200 ml) and the mixture is heated to 90° C. for 3 hours. Formaldehyde(37 wt %, 61.4 g) is then added and the temperature is raised to 130° C.After stirring continuously for five hours, a viscous product,amine-termination Mannich oligomer (AMO), is obtained. The gelpermeation chromatography (GPC) analysis shows three major peaks at Mw3,100, Mw 6,200 and Mw 9,200. Titration for amine of the AMO indicates0.4 meq/g for primary amine, 0.56 meq/g for secondary amine, and zerofor tertiary amine. Then the AMO (57.5 g) is dissolved in water andmixed with concentrated hydrochloric acid (35 wt %, 36 g) at 80° C. for30 minutes to acidify the AMO. The acidified AMO is then added into theNa⁺-MMT dispersion of Step (a). After the mixture is stirred for fivehours, a solution of AMO/Clay is prepared.

Step (c): Buffer solutions with different pH values are added into thesolution of AMO/Clay, which then becomes cream color and viscous.

Step (d): To the viscous solution, ethanol (7.5 L) is added andfiltered. The precipitate is then mixed with ethanol (10 L) and NaOH(9.2 g). The mixture is then filtered to obtain a cream-color,semi-opaque mixture of AMO/Clay which has an organic-to-inorganic ratioof about 40/60.

Step (e): the above mixture of AMO/Clay is added into ethanol (10 L) andNaOH. Water (10 L) and toluene (10 L) are then sequentially added andmixed well with the mixture. After one day, the mixture is divided intothree layers wherein the upper layer is toluene containing the AMO, themiddle layer is ethanol, and the lower layer is water containingnanosilicate platelets (referred to as NSP103S).

The natural or synthetic clay suitable for preparing the NSPs alsoincludes:

a. Bentonite: synthetic layered silicate clay, for example, SWN of CO-OPChemical Co. which has a cationic exchange capacity (CEC) of 0.67mequiv/g.

b. Synthetic fluorine mica, for example, SOMASIF ME-100 of CO-OPChemical Co. which has a CEC of 1.20 mequiv/g.

c. Laponite: synthetic layered silicate clay having a CEC of 0.69mequiv/g.

d. [M^(II) _(1-x)M^(III) _(x)(OH)₂]_(intra)[A^(n−)·nH₂O]_(inter):synthetic layered silicate clay, wherein M^(II) indicates the two-valentmetal ion, for example, Mg, Ni, Cu, or Zn; M^(III) indicates thethree-valent metal ion, for example, Al, Cr, Fe, V, or Ga; A^(n−)indicates the anion, for example, CO₃ ²⁻, NO₃ ²⁻; the anions have ananionic exchange capacity (AEC) from 2.00 to 4.00 mequiv/g.

The Examples described below show the preferred embodiments of thepresent invention, which illustrate, but not limit, the scope of thepresent invention.

EXAMPLE 1

Step (A): To a beaker, NSP103S (9.7 wt %, 0.31 g) and deionic water(89.69 g) are added and the beaker is shaken at room temperature toprepare a solution of NSP 103 (0.033 wt %).

Step (B): To another beaker, Ablumine 1214 (50 wt %, 5.94 g) and deionicwater (4.06 g) are added and mixed with a magnetic stirrer at roomtemperature for 20 minutes to prepare a solution of Ablumine 1214 (29.7wt %).

Step (C): The solutions of Step (A) and Step (B) are then mixed at roomtemperature for one hour and a composite of NSP/Ablumine 1214 having aweight ratio of 1/99 is obtained (referred to as NSS1-D-01) (3 wt %).

EXAMPLE 2

Step (A): To a beaker, NSP103S (9.7 wt %, 29.4 g) and deionic water(60.6 g) are added and the beaker is shaken at room temperature toprepare a solution of NSP 103 (3.2 wt %).

Step (B): To another beaker, Ablumine 1214 (50 wt %, 0.3 g) and deionicwater (9.7 g) are added and mixed with a magnetic stirrer at roomtemperature for 20 minutes to prepare a solution of Ablumine 1214 (1.5wt %).

Step (C): The solutions of Step (A) and Step (B) are then mixed at roomtemperature for one hour and a composite of NSP/Ablumine 1214 having aweight ratio of 95/5 is obtained (referred to as NSS1-D-95) (3 wt %).The procedure is shown in FIG. 1.

EXAMPLE 3

Step (A): To a beaker, NSP103S (9.7 wt %, 30.6 g) and deionic water(59.4 g) are added and the beaker is shaken at room temperature toprepare a solution of NSP 103 (3.3 wt %).

Step (B): To another beaker, Ablumine 1214 (50 wt %, 0.06 g) and deionicwater (9.94 g) are added and mixed with a magnetic stirrer at roomtemperature for 20 minutes to prepare a solution of Ablumine 1214 (0.3wt %).

Step (C): The solutions of Step (A) and Step (B) are then mixed at roomtemperature for one hour and a composite of NSP/Ablumine 1214 having aweight ratio of 99/1 is obtained (referred to as NSS1-D-99) (3 wt %).

EXAMPLE 4

Step (A): To a beaker, NSP103S (9.7 wt %, 0.31 g) and deionic water(89.69 g) are added and the beaker is shaken at room temperature toprepare a solution of NSP 103 (0.033 wt %).

Step (B): To another beaker, SINOPOL 1830 (100 wt %, 2.97 g) and deionicwater (7.03 g) are added and mixed with a magnetic stirrer at roomtemperature for 20 minutes to prepare a solution of SINOPOL 1830 (29.7wt %).

Step (C): The solutions of Step (A) and Step (B) are then mixed at roomtemperature for one hour and a composite of NSP/SINOPOL 1830 having aweight ratio of 1/99 is obtained (referred to as NSS2-D-01) (3 wt %).

EXAMPLE 5

Step (A): To a beaker, NSP103S (9.7 wt %, 29.4 g) and deionic water(60.6 g) are added and the beaker is shaken at room temperature toprepare a solution of NSP 103 (3.2 wt %)

Step (B): To another beaker, SINOPOL 1830 (100 wt %, 0.15 g) and deionicwater (9.85 g) are added and mixed with a magnetic stirrer at roomtemperature for 20 minutes to prepare a solution of SINOPOL 1830 (1.5 wt%).

Step (C): The solutions of Step (A) and Step (B) are then mixed at roomtemperature for one hour and a composite of NSP/SINOPOL 1830 having aweight ratio of 95/5 is obtained (referred to as NSS2-D-95) (3 wt %).The procedure is shown in FIG. 2.

EXAMPLE 6

Step (A): To a beaker, NSP103S (9.7 wt %, 30.6 g) and deionic water(59.4 g) are added and the beaker is shaken at room temperature toprepare a solution of NSP 103 (3.3 wt %)

Step (B): To another beaker, SINOPOL 1830 (100 wt %, 0.03 g) and deionicwater (9.97 g) are added and mixed with a magnetic stirrer at roomtemperature for 20 minutes to prepare a solution of SINOPOL 1830 (0.3 wt%).

Step (C): The solutions of Step (A) and Step (B) are then mixed at roomtemperature for one hour and a composite of NSP/SINOPOL 1830 having aweight ratio of 99/1 is obtained (referred to as NSS2-D-99) (3 wt %).

EXAMPLE 7

Step (A): To a beaker, NSP103S (9.7 wt %, 0.31 g) and deionic water(89.69 g) are added and the beaker is shaken at room temperature toprepare a solution of NSP 103 (0.033 wt %).

Step (B): To another beaker, SDS (100 wt %, 2.97 g) and deionic water(7.03 g) are added and mixed with a magnetic stirrer at room temperaturefor 20 minutes to prepare a solution of SDS (29.7 wt %).

Step (C): The solutions of Step (A) and Step (B) are then mixed at roomtemperature for one hour and a composite of NSP/SINOPOL 1830 having aweight ratio of 1/99 is obtained (referred to as NSS3-A-01) (3 wt %).

EXAMPLE 8

Step (A): To a beaker, NSP103S (9.7 wt %, 29.4 g) and deionic water(60.6 g) are added and the beaker is shaken at room temperature toprepare a solution of NSP 103 (3.2 wt %).

Step (B): To another beaker, SDS (100 wt %, 0.15 g) and deionic water(9.85 g) are added and mixed with a magnetic stirrer at room temperaturefor 20 minutes to prepare a solution of SDS (1.5 wt %).

Step (C): The solutions of Step (A) and Step (B) are then mixed at roomtemperature for one hour and a composite of NSP/SDS having a weightratio of 95/5 is obtained (referred to as NSS3-A-95) (3 wt %).

EXAMPLE 9

Step (A): To a beaker, NSP103S (9.7 wt %, 30.6 g) and deionic water(59.4 g) are added and the beaker is shaken at room temperature toprepare a solution of NSP 103 (3.3 wt %).

Step (B): To another beaker, SDS (100 wt %, 0.03 g) and deionic water(9.97 g) are added and mixed with a magnetic stirrer at room temperaturefor 20 minutes to prepare a solution of SDS (0.3 wt %).

Step (C): The solutions of Step (A) and Step (B) are then mixed at roomtemperature for one hour and a composite of NSP/SDS having a weightratio of 99/1 is obtained (referred to as NSS3-A-99) (3 wt %).

The surfactants and the NSP/surfactant weight ratios of the aboveExamples are shown in ATTACHMENT 2.

In Step (A) and Step (B), the NSPs and the surfactant are preferablydiluted to the same concentration so that the effect of modifying NSPsis better.

[Tests for Inhibiting Growth of Bacteria]

1. Selecting Escherichia coli.

2. Preparing the standard solution of bacteria.

The solution of bacteria incubated overnight is added into a liquidmedium of fresh Luria-Bertani (LB) and is continuously incubated forthree hours. The volumetric ratio of the solution of bacteria to theliquid medium is 1/100. Absorbance of the incubated solution at OD₆₀₀ ismeasured with a spectrophotometer and the solution having OD₆₀₀ rangingfrom 0.4 to 0.6 is selected for the standard solution.

FIG. 3 shows the effects of the NSPs/surfactant complexes of Examples 2,5 and 8 in inhibiting growth of bacteria. The NSPs/surfactant complexeshave a weight ratio of 99/5 and a concentration 0.1 wt %. The resultsindicate that the complex (NSS1-D-95) of Example 2 including thecationic surfactant performs the best effect when the bacteria areelectrically negative.

FIG. 4 shows the effects of the NSPs/surfactant complexes with differentweight ratios in inhibiting growth of bacteria. The results indicatethat the NSPs/surfactant complexes with a weight ratio 50/50 (preparedfrom Examples 2 and 3, NSS1-D-50) perform better effects than that witha weight ratio 95/5 (Example 2, NSS1-D-95), in a concentration of 0.1 wt%. That is, more cationic surfactant facilitates inhibiting growth ofbacteria.

[Tests for Inhibiting Plant Pests]

The NSPs/nonionic surfactant complexes of Examples 4 to 6 arerespectively mixed with alcohol in a weight ratio of 1:2. The mixture isdiluted to 1,000 times and has a concentration 0.001 wt %. Then thesolutions are sprayed on Terminalia boivinii covered with aphides.ATTACHMENT 3 shows that all the pests died after spraying once and thenthe trees grew well without pests.

ATTACHMENTs 4 and 5 respectively compare the results of banana shootsand guava applied with (B) and without (A) the NSPs/surfactant complexof Example 5. The diluted solutions were 0.001 wt %. The picture (B) ofATTACHMENT 4 shows that the banana shoot sprayed with the solution grewobviously better than that shown in the picture (A). The concentrationsand spraying frequencies could influence growing conditions. Compared tothe picture (A) of ATTACHMENT 5, the picture (B) also shows that theguava sprayed with the solution grew faster, flourished leaves, bloomedand fruited more. The complex could also promote growth of vegetablessuch as bottle gourd.

In addition, the dilutions of the exfoliated clay/surfactant complexaccording to the present invention can balance acidic soil and increaseutilization thereof. In the present invention, the exfoliatedclay/surfactant complex is similar to a virus in size, has a largespecific surface area and adsorption ability, so that viruses, bacteriaand pest ova can not proceed with fissiparity or hatch because they areembedded by the complex.

The exfoliated clay/surfactant complex of the present invention arefriendly to the environment and can be further used in other fields, forexample, adsorbing pesticides, promoting aquaculture, treating wastewater of agriculture or fishing, preserving agricultural products,deodorizing corrals or stalls, killing mosquitoes or flies, and cleaningobjects or clothes.

1. An exfoliated clay/surfactant complex for inhibiting microorganisms,viruses or plant pests; wherein: the weight ratio of the exfoliated clayto the surfactant is 99/1 to 1/99; the exfoliated clay is an inorganiclayered clay on a nano scale; and the surfactant is a cationic,nonionic, anionic or amphoteric surfactant.
 2. The exfoliatedclay/surfactant complex of claim 1, wherein the exfoliated clay isnanosilicate platelets (NSPs).
 3. The exfoliated clay/surfactant complexof claim 1, wherein the surfactant is a cationic surfactant and selectedfrom the group consisting of quaternary ammonium salt of a fatty aminehaving 12 to 32 carbon atoms and quaternary ammonium chloride of a fattyamine having 12 to 32 carbon atoms.
 4. The exfoliated clay/surfactantcomplex of claim 1, wherein the surfactant is a cationic surfactant andselected from the group consisting of ammonium chloride of tallow having12 to 18 carbon atoms or ammonium chloride of hydrogenated tallow,quaternary ammonium salt of octadecyl fatty amine, octadecyl ammoniumchloride or alkyl dimethyl benzyl ammonium chloride.
 5. The exfoliatedclay/surfactant complex of claim 1, wherein the cationic surfactant isalkyl dimethyl benzyl ammonium chloride.
 6. The exfoliatedclay/surfactant complex of claim 1, wherein the surfactant is a cationicsurfactant and selected from the group consisting of octylphenolpolyethoxylate and polyoxyethylene alkyl ether.
 7. The exfoliatedclay/surfactant complex of claim 1, wherein the surfactant is a cationicsurfactant and selected from the group consisting of polyoxyethylenealkyl ether, polyoxyethylene stearylcetyl ether, sorbitan esters offatty acids, polysorbates, alkylphenol ethoxylates, nonylphenolethoxylates (NPEOs), and fatty alcohol ethoxylates.
 8. A method forproducing an exfoliated clay/surfactant complex of claim 1, the methodcomprises mixing the exfoliated clay and the surfactant in a solvent toform the complex.
 9. The method of claim 8, wherein the exfoliated clayand the surfactant are respectively dissolved in the solvent, and thenmixed to form the complex.
 10. The method of claim 8, wherein thesolvent is water.